A touchscreen is a display that can detect the presence and location of a touch within the display area. One type of touchscreen is the analog resistive screen which is composed of several layers. When an object, such as a finger, presses down on a point on the screen's outer surface two metallic layers become connected at that point and the screen behaves as a pair of voltage dividers with connected outputs, causing the change in the electrical current to be registered as a touch event. Analog resistive touch screens allow only one point in the screen at a time to be decoded and work with a variety of input methods such as finger, stylus, gloves, and fingernails. It is a durable technology that is used in a wide range of applications including point-of-sale systems, industrial controls, and public information kiosks.
A capacitive touchscreen panel is a sensor typically made of glass coated with a material such as indium tin oxide. The sensor is a capacitor in which the plates are the overlapping areas between the horizontal and vertical axes in a grid pattern. It is a durable technology that is primarily used in consumer portable applications including cell phones and media players. Capacitive touch screens have a higher clarity than analog resistive screens, but they only respond to finger contact and will not work with a gloved hand or pen stylus. Capacitive touch screens can support multi-touch decoding.
Digital resistive touch screens include rows on one layer and columns on an opposite layer, the rows and columns forming a matrix of switches. Digital resistive touch screens are popular when finger size touch zones are required. Interfacing with digital touch screens is as easy as interfacing with a keyboard matrix. However, multi-touch is difficult to decode in digital resistive touch screens.
New applications require multi-touch screens that allow simultaneous detection of multiple touch points to enhance the user-machine interface. Dynamic examples include gesture commands, rotation control, zoom, gaming inputs, etc. Multi-touch applications are still evolving as user interfaces improve with the possibility of multi-touch. Some of the applications that can benefit from multi-touch technology are medical imaging (ultrasound, X-rays, MRI image manipulation), kiosks (photo printing, vending, maps), music and video players, home appliances, etc.
It is in this context that embodiments of the invention arise.